This. (and you could probably reply to 90% of Hanson's 'you can solve problem X with a prediction market' posts with essentially the same argument)

It's not like people with understanding of archaeology aren't already highly incentivised - financially and otherwise - to discover evidence of ancient civilizations if it's actually there. Archaeological frauds exist even now, and even where there is no fraud there are enough disputes in dating and what actually constitutes advanced civilization to guarantee a prediction market in archaeological discovery is going to have a massive oracle problem...

It definitely sets up perverse incentives. Archeological dating is difficult and easy to screw up. Incorrect yet "plausibly deniable" mistakes can get you dates far off from reliably established estimates. There's also a problem of what the end criterion is. Is just publishing a paper in a reputable journal enough? Does it need secondary confirmation, or the decade+ of debate that boundary-pushing finds like Monte Verde require to be established?

You could make that argument about any incentive system. That does not negate the utility of incentives - it simply requires that they are structured correctly to vet evidence.

That's just the natural consequence of a free market. If it is cheaper and easier to hoax, people will do it. It also incentivizes cheaper recovery of archeological artifacts, saving money in the exfiltration process. Not good.